### Abstract

The global geometry of the Universe is in principle as observable an attribute as local curvature. Previous studies have established that if the Universe is wrapped into a flat hypertorus, the simplest compact space, then the fundamental domain must be at least 0.4 times the diameter of the observable Universe. We derive the spectrum of temperature fluctuations for the other five compact, orientable flat spaces and show that the same bound holds for all, although prominent geometric features in sky maps can, in principle, distinguish between these spaces. Our analysis provides the first limits on any of the twisted tori and the hexagonal prisms.

Original language | English (US) |
---|---|

Article number | 103516 |

Pages (from-to) | 1035161-1035165 |

Number of pages | 5 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 58 |

Issue number | 10 |

State | Published - Nov 15 1998 |

Externally published | Yes |

### Fingerprint

### ASJC Scopus subject areas

- Physics and Astronomy(all)
- Nuclear and High Energy Physics
- Mathematical Physics
- Physics and Astronomy (miscellaneous)

### Cite this

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*58*(10), 1035161-1035165. [103516].

**Is the Universe infinite or is it just really big?** / Levin, Janna; Scannapieco, Evan; Silk, Joseph.

Research output: Contribution to journal › Article

*Physical Review D - Particles, Fields, Gravitation and Cosmology*, vol. 58, no. 10, 103516, pp. 1035161-1035165.

}

TY - JOUR

T1 - Is the Universe infinite or is it just really big?

AU - Levin, Janna

AU - Scannapieco, Evan

AU - Silk, Joseph

PY - 1998/11/15

Y1 - 1998/11/15

N2 - The global geometry of the Universe is in principle as observable an attribute as local curvature. Previous studies have established that if the Universe is wrapped into a flat hypertorus, the simplest compact space, then the fundamental domain must be at least 0.4 times the diameter of the observable Universe. We derive the spectrum of temperature fluctuations for the other five compact, orientable flat spaces and show that the same bound holds for all, although prominent geometric features in sky maps can, in principle, distinguish between these spaces. Our analysis provides the first limits on any of the twisted tori and the hexagonal prisms.

AB - The global geometry of the Universe is in principle as observable an attribute as local curvature. Previous studies have established that if the Universe is wrapped into a flat hypertorus, the simplest compact space, then the fundamental domain must be at least 0.4 times the diameter of the observable Universe. We derive the spectrum of temperature fluctuations for the other five compact, orientable flat spaces and show that the same bound holds for all, although prominent geometric features in sky maps can, in principle, distinguish between these spaces. Our analysis provides the first limits on any of the twisted tori and the hexagonal prisms.

UR - http://www.scopus.com/inward/record.url?scp=1542735931&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=1542735931&partnerID=8YFLogxK

M3 - Article

VL - 58

SP - 1035161

EP - 1035165

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 1550-7998

IS - 10

M1 - 103516

ER -