# Giant wormholes in ghost-free bigravity theory

## Abstract

We study Lorentzian wormholes in the ghost-free bigravity theory described by two metrics, g and f. Wormholes can exist if only the null energy condition is violated, which happens naturally in the bigravity theory since the graviton energy-momentum tensors do not apriori fulfill any energy conditions. As a result, the field equations admit solutions describing wormholes whose throat size is typically of the order of the inverse graviton mass. Hence, they are as large as the universe, so that in principle we might all live in a giant wormhole. The wormholes can be of two different types that we call W1 and W2. The W1 wormholes interpolate between the AdS spaces and have Killing horizons shielding the throat. The Fierz-Pauli graviton mass for these solutions becomes imaginary in the AdS zone, hence the gravitons behave as tachyons, but since the Breitenlohner-Freedman bound is fulfilled, there should be no tachyon instability. For the W2 wormholes the g-geometry is globally regular and in the far field zone it becomes the AdS up to subleading terms, its throat can be traversed by timelike geodesics, while the f-geometry has a completely different structure and is not geodesically complete. There is no evidence of tachyonsmore »

- Authors:

- Department of General Relativity and Gravitation, Institute of Physics,Kazan Federal University, Kremlevskaya street 18, 420008 Kazan (Russian Federation)
- (France)

- Publication Date:

- Sponsoring Org.:
- SCOAP3, CERN, Geneva (Switzerland)

- OSTI Identifier:
- 22458351

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 06; Other Information: PUBLISHER-ID: JCAP06(2015)017; OAI: oai:repo.scoap3.org:10622; Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANTI DE SITTER SPACE; ENERGY-MOMENTUM TENSOR; FIELD EQUATIONS; GEODESICS; GEOMETRY; GRAVITATION; GRAVITONS; LORENTZ INVARIANCE; MATHEMATICAL SOLUTIONS; METRICS; NONLUMINOUS MATTER; TACHYONS; UNIVERSE

### Citation Formats

```
Sushkov, Sergey V., Volkov, Mikhail S., and Laboratoire de Mathématiques et Physique Théorique CNRS-UMR 7350, Université de Tours, Parc de Grandmont, 37200 Tours.
```*Giant wormholes in ghost-free bigravity theory*. United States: N. p., 2015.
Web. doi:10.1088/1475-7516/2015/06/017.

```
Sushkov, Sergey V., Volkov, Mikhail S., & Laboratoire de Mathématiques et Physique Théorique CNRS-UMR 7350, Université de Tours, Parc de Grandmont, 37200 Tours.
```*Giant wormholes in ghost-free bigravity theory*. United States. doi:10.1088/1475-7516/2015/06/017.

```
Sushkov, Sergey V., Volkov, Mikhail S., and Laboratoire de Mathématiques et Physique Théorique CNRS-UMR 7350, Université de Tours, Parc de Grandmont, 37200 Tours. Tue .
"Giant wormholes in ghost-free bigravity theory". United States.
doi:10.1088/1475-7516/2015/06/017.
```

```
@article{osti_22458351,
```

title = {Giant wormholes in ghost-free bigravity theory},

author = {Sushkov, Sergey V. and Volkov, Mikhail S. and Laboratoire de Mathématiques et Physique Théorique CNRS-UMR 7350, Université de Tours, Parc de Grandmont, 37200 Tours},

abstractNote = {We study Lorentzian wormholes in the ghost-free bigravity theory described by two metrics, g and f. Wormholes can exist if only the null energy condition is violated, which happens naturally in the bigravity theory since the graviton energy-momentum tensors do not apriori fulfill any energy conditions. As a result, the field equations admit solutions describing wormholes whose throat size is typically of the order of the inverse graviton mass. Hence, they are as large as the universe, so that in principle we might all live in a giant wormhole. The wormholes can be of two different types that we call W1 and W2. The W1 wormholes interpolate between the AdS spaces and have Killing horizons shielding the throat. The Fierz-Pauli graviton mass for these solutions becomes imaginary in the AdS zone, hence the gravitons behave as tachyons, but since the Breitenlohner-Freedman bound is fulfilled, there should be no tachyon instability. For the W2 wormholes the g-geometry is globally regular and in the far field zone it becomes the AdS up to subleading terms, its throat can be traversed by timelike geodesics, while the f-geometry has a completely different structure and is not geodesically complete. There is no evidence of tachyons for these solutions, although a detailed stability analysis remains an open issue. It is possible that the solutions may admit a holographic interpretation.},

doi = {10.1088/1475-7516/2015/06/017},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 06,

volume = 2015,

place = {United States},

year = {Tue Jun 09 00:00:00 EDT 2015},

month = {Tue Jun 09 00:00:00 EDT 2015}

}