### Abstract

We study a generality of an inflationary scenario by integrating the Einstein equations numerically in a plane-symmetric spacetime. We consider the inhomogeneous spacetimes due to (i) localized gravitational waves with a positive cosmological constant Λ and (ii) an inhomogeneous inflation field Φ with a potential 12m2Φ2. For case (i), we find that any initial inhomogeneities are smoothed out even if waves collide, so that we conclude that inhomogeneity due to gravitational waves does not prevent the onset of inflation. As for case (ii), if the mean value of the inflaton field is initially as large as the condition in an isotropic and homogeneous inflationary model (i.e., the mean value is larger than several times the Planck mass), the field is soon homogenized and the universe always evolves into de Sitter spacetime. This supports the cosmic no hair conjecture in a planar universe. We also discuss the effects of an additional massless scalar field, which are introduced to set initial data in the usual analysis.

Original language | English |
---|---|

Pages (from-to) | 6367-6378 |

Number of pages | 12 |

Journal | Physical Review D |

Volume | 49 |

Issue number | 12 |

DOIs | |

Publication status | Published - 1994 |

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### ASJC Scopus subject areas

- Physics and Astronomy (miscellaneous)

### Cite this

*Physical Review D*,

*49*(12), 6367-6378. https://doi.org/10.1103/PhysRevD.49.6367

**Generality of inflation in a planar universe.** / Shinkai, Hisa Aki; Maeda, Keiichi.

Research output: Contribution to journal › Article

*Physical Review D*, vol. 49, no. 12, pp. 6367-6378. https://doi.org/10.1103/PhysRevD.49.6367

}

TY - JOUR

T1 - Generality of inflation in a planar universe

AU - Shinkai, Hisa Aki

AU - Maeda, Keiichi

PY - 1994

Y1 - 1994

N2 - We study a generality of an inflationary scenario by integrating the Einstein equations numerically in a plane-symmetric spacetime. We consider the inhomogeneous spacetimes due to (i) localized gravitational waves with a positive cosmological constant Λ and (ii) an inhomogeneous inflation field Φ with a potential 12m2Φ2. For case (i), we find that any initial inhomogeneities are smoothed out even if waves collide, so that we conclude that inhomogeneity due to gravitational waves does not prevent the onset of inflation. As for case (ii), if the mean value of the inflaton field is initially as large as the condition in an isotropic and homogeneous inflationary model (i.e., the mean value is larger than several times the Planck mass), the field is soon homogenized and the universe always evolves into de Sitter spacetime. This supports the cosmic no hair conjecture in a planar universe. We also discuss the effects of an additional massless scalar field, which are introduced to set initial data in the usual analysis.

AB - We study a generality of an inflationary scenario by integrating the Einstein equations numerically in a plane-symmetric spacetime. We consider the inhomogeneous spacetimes due to (i) localized gravitational waves with a positive cosmological constant Λ and (ii) an inhomogeneous inflation field Φ with a potential 12m2Φ2. For case (i), we find that any initial inhomogeneities are smoothed out even if waves collide, so that we conclude that inhomogeneity due to gravitational waves does not prevent the onset of inflation. As for case (ii), if the mean value of the inflaton field is initially as large as the condition in an isotropic and homogeneous inflationary model (i.e., the mean value is larger than several times the Planck mass), the field is soon homogenized and the universe always evolves into de Sitter spacetime. This supports the cosmic no hair conjecture in a planar universe. We also discuss the effects of an additional massless scalar field, which are introduced to set initial data in the usual analysis.

UR - http://www.scopus.com/inward/record.url?scp=0011596647&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0011596647&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.49.6367

DO - 10.1103/PhysRevD.49.6367

M3 - Article

AN - SCOPUS:0011596647

VL - 49

SP - 6367

EP - 6378

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 0556-2821

IS - 12

ER -