Giant wormholes in ghost-free bigravity theory

Understand

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.